Understanding calcium functionality by examining growth characteristics and structural aspects in calcium-deficient grapevine.

This study characterized growth characteristics and cellular details employing microscopy techniques in hydroponically-grown Ca-sufficient and Ca-deficient grapevines (Vitis vinifera) in a glasshouse. The Ca-deficient vines exhibited significant reductions in shoot length, shoot and trunk fresh weights, leaf area, chlorophyll, which eventually led to drooping, yellowing, and chlorosis of leaves. Roots were less dense and primarily dark and necrotic. Furthermore, their xylem vessels were small, polygonal, and appeared to be collapsed yet increased in number and developed lateral roots. Despite such alterations, the anatomical organization of leaves was not affected, yet they developed with more xylem vessels with thick walls and lignin in their mesophyll and vascular tissues. The chloroplasts in internodes' chlorenchyma, phloem, and cambium underwent significant ultrastructural modifications. The concentrations of macro and micronutrients varied significantly among the roots, trunk, canes, and leaves, including the growth characteristics. These structural and growth modifications of calcium deficiency enable us to understand better the link between the symptoms and functions and for a holistic understanding of Ca functionalities.